Public domain
Chicago, Illinois. Cars are uncoupled at the top of the hump and roll down by gravity at an Illinois Central Railroad yard to the classification yards
From the collection of Library of Congress. Free to download, adapt and use — no permission needed.
Credit lineChicago, Illinois. Cars are uncoupled at the top of the hump and roll down by gravity at an Illinois Central Railroad yard to the classification yards. 1942-01-01. Delano, Jack. Farm Security Administration/Office of War Information Collection, Library of Congress. Public domain.